PROJECT SUMMARY The goal of the current project is to elaborate upon, reconstruct and advance to pivotal trial readiness a multimodal, closed loop assessment-to-treatment mobile application for individuals with mood disorders. Major Depressive Disorder (MDD) is a recurrent and disabling condition, and a leading cause of global disease burden. Nearly half of the patients fail to respond to psychological or pharmacological treatments due in part to inaccessibility of treatments outside the clinic, discontinuity of connection with treatment providers and difficulty in complying with demanding treatment regimens. In the current proposal, we aim to bridge these large treatment gaps by finalizing the development of Moodify, a mobile mental health application designed to provide continuous, multi-modal mood monitoring and individualized treatments via a closed-loop algorithm. Moodify is designed to be used as an adjunct to conventional treatment, allowing clinicians to remotely track their patients? status and changes in mood between clinic visits, and to refine treatment parameters to maximize potential treatment benefits. Moodify?s innovative assessment approach documents mood using a combination of active and passive monitoring strategies; It?s innovative treatment approach uses a closed-loop algorithm that determines, based on current mood state reading and the patient?s status, which treatment to apply, how to apply it and when to apply it, in an effort to optimize treatment benefits. The Moodify platform supports delivery of various treatment options, including CBT, relaxation techniques and plasticity-based cognitive training. Preliminary testing of initial prototypes of Moodify in MDD patients and matched controls showed promising results of the Moodify approach, demonstrating its effectiveness in capturing mood states quickly and reliably over time. In the proposed project, we plan to finalize Moodify?s development, to ensure users engagement over longer time periods, and conduct a feasibility trial in the target population of patients with MDD, monitored by their clinicians. In the first specific aim, we will improve upon existing beta version of the application with feedback from small focus groups composed of individuals with mood disruption and clinicians to ensure that the user experience and the user interface are sufficient to motivate four weeks of program use. Using established methods of software design and development, we will iteratively refine the implemented design to complete the development of the enhanced program and conduct the feasibility trial. At the completion of this project we will have data sufficient to propose a multi-site, randomized, controlled medical device trial designed to establish medical claims defining the efficacy of this mobile program.